The problems with the diagnosis of Parkinson’s Disease in Malaysia
Currently, there are no official statistics on the prevalence of Parkinson’s Disease (PD) in Malaysia. However, based on the total consumption of levodopa in Malaysia in 1999, the estimated annual number of levodopa-treated patients was 1,113. This number was derived by dividing the total national levodopa consumption in 1999 (191,800,000 mg; based on sales figures of Roche, a pharmaceutical company) with the estimated annual consumption of levodopa per patient (172,280 mg; based on the study by Chew NK, Goh KJ and Tan CT, 1998). This calculation employed the assumption that throughout 1999: a) all the patients were taking a constant dose of levodopa, b) there were no newly diagnosed patients, and c) all patients sought treatment at the hospitals and clinics.
Strictly speaking, the most accurate study on the prevalence of PD would be a “door-to door” study in the community. A previous “door-to-door” study in the People’s Republic of China had shown that the prevalence of PD was 50 per 100,000 population (Li SC et al, 1985). If we assume that the prevalence of PD in Malaysia in 1999 was the same as that of the People’s Republic of China, the total number of Parkinson’s patients in Malaysia is expected to be 12,500. This figure is far higher than the estimate of 1,113 levodopa-treated patients.
Based on personal experience, I believe that the total number of Parkinson’s patients in Malaysia is most likely 15 000, or even higher. Thus, PD is most likely under-diagnosed in Malaysia. The Parkinson’s patients that are seen in the hospitals and clinics are merely the “tip of the iceberg”.
In addition, there is also a problem of late diagnosis in PD. In a previous study carried out on 153 Parkinson’s patients seen at University Hospital, it was found that the symptoms were already present for an average of 22 months before they sought medical advice (Chew NK, Goh KJ and Tan CT, 1998).
There are several reasons that can account for the under-diagnosis and late diagnosis of PD in Malaysia:
a) the lack of public awareness
The lack of awareness of PD among the public has been briefly discussed previously. Many people are not well informed about the early symptoms. As there is hardly any publicity on PD in the mass media, this remains one of the less recognized diseases in Malaysia.
b) the lack of neurological services
The shortage of neurologists is a major problem in Malaysia. There is roughly one neurologist for each million population. To complicate the situation, there is an uneven distribution of such specialists in Malaysia – about 96% of them are currently working in West Malaysia. Even in West Malaysia, about 90% of them are serving in the Klang Valley. Consequently, most Parkinson’s patients are first seen by general practitioners who may not be familiar with the diagnosis of PD.
c) the characteristics of PD itself
There are several peculiar characteristics of PD that hamper the early diagnosis. This diagnostic difficulty is compounded by the general lack of awareness of PD among both the public and medical personnel in Malaysia.
i) The insidious nature of the onset of PD
The early symptoms of PD start very slowly and in a silent manner. Consequently, many patients themselves do not realize the onset of illness. Occasionally, some observant spouses are the first to notice the slowness of movement without knowing the exact cause. Some of my patients’ wives commented that their husbands could no longer catch up with them while walking at the supermarkets. Prior to that, it was their husbands who walked in front of them, leaving their wives and children behind! Some family members and friends may notice that the patient’s voice has become softer and slurred during daily conversation.
“Following an episode of chicken pox two years ago, I started to become weak, particularly at the right side of my body. I became tired easily. Gradually, the weakness spread to the whole body. My business was affected until the stage of bankruptcy. I was very worried, depressed and frightened. As days went by, I started to have tremors and walked slower than before. Initially, my wife and I thought it was due to the aftermath of the chicken pox infection. My problem went on until one day, my wife noticed that I could no longer remove the identity card from my wallet. It was at this time that she thought I should seek medical treatment”.
ii) the non-specific and vague nature of the early symptoms.
When the predominant symptoms are slowness of movement and weakness, some people think that they are having other medical conditions such as heart failure and lung disease. More often, the early symptoms of PD are confused with the natural ageing process. As a result, patients consult doctors only after the illness has progressed to the late stage when they cannot carry out the daily activities anymore.
“As my early symptoms were rather vague, both my family doctor and I initially thought that I had heart problem. However, the heart specialist did not find anything wrong with my heart. Finally, I was referred to a neurologist who then diagnosed me as having PD”.
Even when the doctor suspects the presence of PD, the diagnosis is not that straightforward. This is because the early symptoms and signs of PD are not specific to this disorder; they are also found in many other neurological disorders that cause parkinsonism. There are no specific abnormalities on blood tests or brain scans that can diagnose PD and differentiate it from other types of parkinsonism.
Sometimes, the subtle signs of early PD may be confused with a different illness, essential tremor (ET). The tremor of ET also involves the hands and legs, thus making it difficult to distinguish from PD.
Another reason for the confusion between PD and ET is that both illnesses affect the elderly. Once, I met an elderly lady who had been having hand tremor for 20 years. She had been treated with levodopa for ten years as her family doctor initially diagnosed PD. When I reviewed her, I found that she actually had ET. After explaining the diagnosis, I started her on propranolol (the drug for treating ET). Three months later, the patient was back on levodopa again because her daughter found it too hard to accept the fact that her diagnosis could be changed after such a long time!
The diagnosis of PD is one of the most challenging in medical practice. The peculiar characteristics of PD, together with all the limitations in health resources, contribute to the diagnostic problems of PD in Malaysia. As Roger Duvoisin, the famous neurologist, once said, “the diagnosis of PD with mild symptoms of recent onset can tax the skills of the most experienced and astute clinician. Its difficulty should not be under-estimated.”
Chew NK, Goh KJ, Tan CT. Parkinson’s Disease in University Hospital, Kuala Lumpur. Neurol J Southeast Asia 1998; 3: 75-80.
Li SC, Schoenberg BS, Wang CC, Cheng XM, et al. A prevalence survey of Parkinson’s Disease and other movement disorders in the People’s republic of China. Arch Neurol 1985; 42: 655-657.